convert2NTtime(curr_time)

function total_100ns_ints = convert2NTtime(curr_time)
%curr_time = date vector with the format [year month day hour minute seconds]
%total_100ns_int = number of 100 nanosecond intervals that have passed
%                  since the time specified by the date vector
%
%This program is used to convert the current date and time to the number of
%100 nanosecond intervals that have passed since January 1, 1601, which is
%the time format that Windows NT uses.
%
%Josiah Renfree
%April 2, 2007

curr_year = curr_time(1);
curr_month = curr_time(2);
curr_day = curr_time(3);
curr_hour = curr_time(4);
curr_minute = curr_time(5);
curr_second = curr_time(6);

%***************** 100 ns intervals in previous years ********************
%--- find number of years that have passed
diff_years = curr_year - 1601;

%--- Determine how many of those years are leap years
years=1601:curr_year-1;
mask400 = find(mod(years,400) == 0);
mask100 = find(mod(years,100) == 0);
mask4 = find(mod(years,4) == 0);

num_leap_years = length(mask4) - length(mask100) + length(mask400);

%--- Calculate number of days excluding the current year
numdays_nly = (length(years) - num_leap_years).*365;
numdays_ly = num_leap_years.*366;
previous_days = numdays_nly + numdays_ly;

%--- Convert previous years to number of 100 nanosecond intervals
previous_hours = previous_days*24;
previous_minutes = previous_hours*60;
previous_seconds = previous_minutes*60;
previous_ns = previous_seconds*10^9;

previous_num_100ns_int = previous_ns/100;
%*************************************************************************



%************* 100 ns intervals in previous days of current year *********
%--- find number of months that have passed in current year
diff_months = curr_month - 1;
date_vec = [31 28 31 30 31 30 31 31 30 31 30 31];

%if current year is leap year
if mod(curr_year,400) == 0
    leap = 1;
elseif mod(curr_year,100) == 0
    leap = 0;
elseif mod(curr_year,4) == 0
    leap = 1;
else
    leap = 0;
end

%--- Calculate number of full days elapsed in current year ----
months2days = sum(date_vec(1:diff_months));

%if month conversion included leap year day
if leap == 1 & curr_month > 2
    months2days = months2days + 1;
end

days_elapsed = curr_day - 1;

full_days_elapsed = months2days + days_elapsed;
%--------------------------------------------------------------

%--- Convert to number of 100 nanosecond intervals
full_100ns_int = (full_days_elapsed*24*60*60*10^9)/100;
%*************************************************************************


%************* 100 ns intervals in current day ***************************
%--- Calculate number of 100 ns intervals in current day
hours2ns = curr_hour * 60 * 60 * 10^9;
minutes2ns = curr_minute * 60 * 10^9;
seconds2ns = curr_second * 10^9;

curr_day_100ns_int = (hours2ns + minutes2ns + seconds2ns)/100;
%*************************************************************************

%--- Combine all the calculations
total_100ns_ints = curr_day_100ns_int + full_100ns_int + previous_num_100ns_int;